History Of The 136th Radio Security Detachment, 7 February 1942 To 30 April 1946 1946-05-20
"Radio transmission security is a little understood subject in the Amy Air Forces at the beginning of the recent war. Training manuals referred to radio security in a brief paragraph or two, with casual statements to the effect that it was possible for the enemy to obtain information from friendly radio transmissions. The regulations covering the subject were for the most part adequate but there appeared to be little awareness of their existence on the part of most communications personnel. The difficulty of training large numbers of pilots and radio operators was tremendous. There was little time for drilling in procedures and security measures until they became a matter of habit."
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